How would I manipulate string to use through HttpService?

I recently asked a question "How to Gather Certain Locations in HttpService?", as I do not know how to gather certain locations of string. The person who answered this question adark said to "Manipulate String", but I do not know how.. He said use hurl.it, but I do not know how.. So say I wanted to gather the group members of a group, how would I do that??? I do not know, I just know how to gather full data, that's it. How would I change this

print(game:GetService("HttpService"):GetAsync("http://rproxy.pw/My/Groups.aspx?gid=2672295"))

Where it only shows the Group Members string / value?